/**
 * \file aes.h
 *
 * \brief AES block cipher
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org) and was downloaded from
 *  https://github.com/Secure-Embedded-Systems/RSA-example/tree/master/include/.
 */
#ifndef AES_H
#define AES_H

#include <stddef.h>
#include <stdint.h>

#define AES_ENCRYPT                     1
#define AES_DECRYPT                     0

#define ERR_AES_INVALID_KEY_LENGTH     -0x0020  /**< Invalid key length. */
#define ERR_AES_INVALID_INPUT_LENGTH   -0x0022  /**< Invalid data input length. */

#ifdef __cplusplus
extern "C" {
#endif

    /**
     * \brief          AES context structure
     *
     * \note           buf is able to hold 32 extra bytes, which can be used:
     *                 - for alignment purposes if VIA padlock is used, and/or
     *                 - to simplify key expansion in the 256-bit case by
     *                 generating an extra round key
     */
    typedef struct
    {
        int nr;                     /*!<  number of rounds  */
        uint32_t* rk;               /*!<  AES round keys    */
        uint32_t buf[68];           /*!<  unaligned data    */
    }
    aes_context;

    /**
     * \brief          Initialize AES context
     *
     * \param ctx      AES context to be initialized
     */
    void aes_init(aes_context* ctx);

    /**
     * \brief          Clear AES context
     *
     * \param ctx      AES context to be cleared
     */
    void aes_free(aes_context* ctx);

    /**
     * \brief          AES key schedule (encryption)
     *
     * \param ctx      AES context to be initialized
     * \param key      encryption key
     * \param keybits  must be 128, 192 or 256
     *
     * \return         0 if successful, or ERR_AES_INVALID_KEY_LENGTH
     */
    int aes_setkey_enc(aes_context* ctx, const uint8_t* key, unsigned int keybits);

    /**
     * \brief          AES key schedule (decryption)
     *
     * \param ctx      AES context to be initialized
     * \param key      decryption key
     * \param keybits  must be 128, 192 or 256
     *
     * \return         0 if successful, or ERR_AES_INVALID_KEY_LENGTH
     */
    int aes_setkey_dec(aes_context* ctx, const uint8_t* key, unsigned int keybits);

    /**
     * \brief          AES-ECB block encryption/decryption
     *
     * \param ctx      AES context
     * \param mode     AES_ENCRYPT or AES_DECRYPT
     * \param input    16-byte input block
     * \param output   16-byte output block
     *
     * \return         0 if successful
     */
    int aes_crypt_ecb(aes_context* ctx, int mode, const uint8_t input[16], uint8_t output[16]);

    /**
     * \brief          AES-CBC buffer encryption/decryption
     *                 Length should be a multiple of the block
     *                 size (16 bytes)
     *
     * \note           Upon exit, the content of the IV is updated so that you can
     *                 call the function same function again on the following
     *                 block(s) of data and get the same result as if it was
     *                 encrypted in one call. This allows a "streaming" usage.
     *                 If on the other hand you need to retain the contents of the
     *                 IV, you should either save it manually or use the cipher
     *                 module instead.
     *
     * \param ctx      AES context
     * \param mode     AES_ENCRYPT or AES_DECRYPT
     * \param length   length of the input data
     * \param iv       initialization vector (updated after use)
     * \param input    buffer holding the input data
     * \param output   buffer holding the output data
     *
     * \return         0 if successful, or ERR_AES_INVALID_INPUT_LENGTH
     */
    int aes_crypt_cbc(aes_context* ctx, int mode, size_t length, uint8_t iv[16],
                      const uint8_t* input, uint8_t* output);

    /**
     * \brief          AES-CFB128 buffer encryption/decryption.
     *
     * Note: Due to the nature of CFB you should use the same key schedule for
     * both encryption and decryption. So a context initialized with
     * aes_setkey_enc() for both AES_ENCRYPT and AES_DECRYPT.
     *
     * \note           Upon exit, the content of the IV is updated so that you can
     *                 call the function same function again on the following
     *                 block(s) of data and get the same result as if it was
     *                 encrypted in one call. This allows a "streaming" usage.
     *                 If on the other hand you need to retain the contents of the
     *                 IV, you should either save it manually or use the cipher
     *                 module instead.
     *
     * \param ctx      AES context
     * \param mode     AES_ENCRYPT or AES_DECRYPT
     * \param length   length of the input data
     * \param iv_off   offset in IV (updated after use)
     * \param iv       initialization vector (updated after use)
     * \param input    buffer holding the input data
     * \param output   buffer holding the output data
     *
     * \return         0 if successful
     */
    int aes_crypt_cfb128(aes_context* ctx, int mode, size_t length, size_t* iv_off,
                         uint8_t iv[16], const uint8_t* input, uint8_t* output);

    /**
     * \brief          AES-CFB8 buffer encryption/decryption.
     *
     * Note: Due to the nature of CFB you should use the same key schedule for
     * both encryption and decryption. So a context initialized with
     * aes_setkey_enc() for both AES_ENCRYPT and AES_DECRYPT.
     *
     * \note           Upon exit, the content of the IV is updated so that you can
     *                 call the function same function again on the following
     *                 block(s) of data and get the same result as if it was
     *                 encrypted in one call. This allows a "streaming" usage.
     *                 If on the other hand you need to retain the contents of the
     *                 IV, you should either save it manually or use the cipher
     *                 module instead.
     *
     * \param ctx      AES context
     * \param mode     AES_ENCRYPT or AES_DECRYPT
     * \param length   length of the input data
     * \param iv       initialization vector (updated after use)
     * \param input    buffer holding the input data
     * \param output   buffer holding the output data
     *
     * \return         0 if successful
     */
    int aes_crypt_cfb8(aes_context* ctx, int mode, size_t length, uint8_t iv[16],
                       const uint8_t* input, uint8_t* output);

    /**
     * \brief               AES-CTR buffer encryption/decryption
     *
     * Warning: You have to keep the maximum use of your counter in mind!
     *
     * Note: Due to the nature of CTR you should use the same key schedule for
     * both encryption and decryption. So a context initialized with
     * aes_setkey_enc() for both AES_ENCRYPT and AES_DECRYPT.
     *
     * \param ctx           AES context
     * \param length        The length of the data
     * \param nc_off        The offset in the current stream_block (for resuming
     *                      within current cipher stream). The offset pointer to
     *                      should be 0 at the start of a stream.
     * \param nonce_counter The 128-bit nonce and counter.
     * \param stream_block  The saved stream-block for resuming. Is overwritten
     *                      by the function.
     * \param input         The input data stream
     * \param output        The output data stream
     *
     * \return         0 if successful
     */
    int aes_crypt_ctr(aes_context* ctx, size_t length, size_t* nc_off, uint8_t nonce_counter[16],
                      uint8_t stream_block[16], const uint8_t* input, uint8_t* output);

    /**
     * \brief           Internal AES block encryption function
     *                  (Only exposed to allow overriding it,
     *                  see AES_ENCRYPT_ALT)
     *
     * \param ctx       AES context
     * \param input     Plaintext block
     * \param output    Output (ciphertext) block
     */
    void aes_encrypt(aes_context* ctx, const uint8_t input[16], uint8_t output[16]);

    /**
     * \brief           Internal AES block decryption function
     *                  (Only exposed to allow overriding it,
     *                  see AES_DECRYPT_ALT)
     *
     * \param ctx       AES context
     * \param input     Ciphertext block
     * \param output    Output (plaintext) block
     */
    void aes_decrypt(aes_context* ctx, const uint8_t input[16], uint8_t output[16]);

#ifdef __cplusplus
}
#endif

#endif /* aes.h */
